Intermittent frequent timeouts, 403 and 503 errors

We have frequent intermittent downtimes. UptimeRobot reports 403, 502, and timeout errors lingering from 3 minutes to 1 hour. It was working fine for a long once, but this started happening very often during the last month, without any changes to website set-up. Are there frequent issues with Couldflare lately? What steps can we take to troubleshoot it?